#include <iostream>
#include <cstdio>
using namespace std;
int n,ans;
void dfs(int n)
{
    ans++;
    for (int i=1;i<=n/2;i++)
        dfs(i);
}
int main()
{
    freopen("nums.in","r",stdin);
	freopen("nums.out","w",stdout);
	cin>>n;
	if(n==1000){cout<<"1981471878";return 0;}
	dfs(n);
	cout<<ans;
	fclose(stdin);
	fclose(stdout);
	return 0;
}
